A
thousand miles south of Hawaii, the air at 45,000 feet above the
equatorial Pacific was a shimmering gumbo of thick storm clouds and icy
cirrus haze, all cooked up by the overheated waters below.

In a Gulfstream jet more accustomed to hunting hurricanes in the Atlantic, researchers with the National Oceanic and Atmospheric Administration
were cruising this desolate stretch of tropical ocean where the
northern and southern trade winds meet.
It’s an area that becalmed
sailors have long called the doldrums, but this year it is anything but
quiet.

This
is the heart of the strongest El Niño in a generation, one that is
pumping moisture and energy into the atmosphere and, as a result, roiling weather worldwide.

A satellite image of the area of the Pacific where a NOAA research team would be flying.

Kent Nishimura for The New York Times

The plane, with 11 people aboard including a journalist, made its way
Friday on a long westward tack, steering clear of the worst of the
disturbed air to the south.
Every 10 minutes, on a countdown from Mike
Holmes, one of two flight directors, technicians in the rear released an
instrument package out through a narrow tube in the floor.
Slowed by a
small parachute, the devices, called dropsondes,
fell toward the water, transmitting wind speed and direction, humidity
and other atmospheric data back to the plane continuously on the way
down.

Leonard Miller, a NOAA
technician, left, testing an instrument package called a dropsonde that
was set to be launched from the plane’s delivery system, right.

Credit
Left, Henry Fountain/The New York Times; right, Kent Nishimura for The New York Times

The
information, parsed by scientists and fed into weather models, may
improve forecasting of El Niño’s effect on weather by helping
researchers better understand what happens here, at the starting point.

“One
of the most important questions is to resolve how well our current
weather and climate models do in representing the tropical atmosphere’s
response to an El Niño,” said Randall Dole, a senior scientist at NOAA’s
Earth System Research Laboratory and one of the lead researchers on the project. “It’s the first link in the chain.”

An
El Niño forms about every two to seven years, when the surface winds
that typically blow from east to west slacken.
As a result, warm water
that normally pools along the Equator in the western Pacific piles up
toward the east instead.
Because of this shift, the expanse of water —
which in this El Niño has made the central and eastern Pacific as much
as 5 degrees Fahrenheit hotter than usual — acts as a heat engine,
affecting the jet streams that blow at high altitudes.

That,
in turn, can bring more winter rain to the lower third of the United
States and dry conditions to southern Africa, among El Niño’s many
possible effects.

Aided
by vast processing power and better data, scientists have improved the
ability of their models to predict when an El Niño will occur and how
strong it will be.
As early as last June, the consensus among
forecasters using models developed by NOAA, as well as other American
and foreign agencies and academic institutions, was that a strong El
Niño would develop later in the year, and it did.

But
scientists have been less successful at forecasting an El Niño’s effect
on weather.

This year, for instance, most models have been less certain
about what it will mean for parched California.

So far, much of the
state has received higher than usual precipitation, but it is still
unclear whether Southern California, especially, will be deluged as much as it was during the last strong El Niño, in 1997-98.

Anthony
Barnston, the chief forecaster at the International Research Institute
for Climate and Society at Columbia University, who has studied the
accuracy of El Niño modeling, said that so-called dynamical models,
which simulate the physics of the real world, have recently done a
better job in predicting whether an El Niño will occur than statistical
models, which rely on comparisons of historical data.

With
a dynamical model, Dr. Barnston said, data representing current
conditions is fed into the model, and off it goes.

“You plug it in and
you crank it forward in time,” he said.

This can be done dozens of times
— or as often as money will allow — tweaking the data slightly each
time and averaging the outcomes.

With
any model, good data is crucial.

El Niño models have been helped by the
development of satellites and networks of buoys that can measure
sea-surface temperatures and other ocean characteristics.

When
it comes to forecasting El Niño’s weather effects, however, good data
can be harder to come by.

That’s where the NOAA research project aims to
help, by studying a key process in the El Niño-weather connection: deep
tropical convection.

Alan S. Goldstein, the radar monitor for the mission, with other researchers before the flight.

Credit Kent Nishimura for The New York Times

The
clouds that the NOAA jet cruised past on Friday were a result of this
process, in which air over the warm El Niño waters picks up heat and
moisture and rises tens of thousands of feet.

When the air reaches high
altitudes — about the flight level of the Gulfstream — the moisture
condenses into droplets, releasing energy in the form of heat and
creating winds that flow outward.

Scientists
know that the energy released can induce a kind of ripple in a jet
stream, a wave that as it travels along can affect weather in disparate
regions around the world.

And they know that the winds that are
generated can add a kick to a jet stream, strengthening it. That’s a
major reason California and much of the southern United States tend to
be wetter in an El Niño; the winds from convection strengthen the jet
stream enough that it reaches California and beyond.

But
to study convection during an El Niño, data must be collected from the
atmosphere as well as the sea surface.

That’s a daunting task, because
the convection occurs in one of the most remote areas of the planet. As a
result, there has been little actual data on convection during El Niño
events, Dr. Dole said, and most models, including NOAA’s own, have had
to make what amount to educated guesses about the details of the
process.

“Our
strong suspicion is that our models have major errors in reproducing
some of these responses,” he said.

“The only way we can tell is by going
out and doing observations.”

When
forecasters last year began to predict a strong El Niño, the NOAA
scientists saw an opportunity and started making plans for a
rapid-response program of research.

Dr. Dole estimated that it would normally take two or three years to put together a program they assembled in about six months.

In
a way, he said, they were helped by the developing El Niño, which
suppressed hurricane activity in the Atlantic last fall.

The Gulfstream
flew fewer missions and the available flight hours, as well as extra
dropsondes, were transferred to the project.

In
addition to the jet — which is also equipped with Doppler radar to
study wind — the program is launching other sondes, from a ship and a
small atoll near the Equator.

A large remotely piloted aircraft from
NASA, the Global Hawk, has also been enlisted to study the Pacific
between Hawaii and the mainland.

The
Gulfstream flight Friday was the researchers’ fourth so far, out of
nearly two dozen planned over the next month.

The day began at Honolulu
International Airport five hours before the 11:30 a.m. takeoff when Ryan
Spackman, the other lead investigator, and NOAA colleagues sat down for
a weather briefing with Dr. Dole and other scientists at the agency’s
offices in Boulder, Colo.

The
original plan was to fly due south from Honolulu and around an area of
convection — a “cell” in meteorological terms — near the Equator.

But
when the plane’s three pilots arrived for their briefing several hours
later, the plan was changed out of safety concerns.

There was a risk
they would have no way to get back from the south side of the convection
area without going through a storm, and the Gulfstream, unlike NOAA’s
other hurricane-hunting planes, cannot do that.